Device for setting the rolling space in a rolling mill



April 20, 1965 E. ANGEID 3,178,918

DEVICE FOR SETTING THE ROLLING SPACE IN A ROLLING MILL Filed Nov. 14, 1961 Fig.1

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United States Patent O 3,178,918 DEVICE FOR SETTING THE ROLLING SPACE IN A ROLLING MILL Egil Angeid, Vasteras, Sweden, assignor to Allmiinna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, 2 Swedish corporation Filed Nov. 14, 1961, Ser. No. 152,272 Claims priority, application Sweden, Nov. 29, 1960, 11,497/ 60 5 Claims. (Cl. 72- 8) The present invention relates to a device for automatically setting a pre-determined rolling space between a pair of rolls.

A pair of rolls in a rolling mill is usually arranged so that one roll is mounted in a movable bearing housing which, under influence from a mechanical driving means, the so-called mill screw which in its turn is driven by an electrical motor, may be moved in relation to the other roll so that a variable distance, rolling space, between the two rolls may be obtained. To preset a certain desired rolling space, the so-called zero space, there are normally mechanically rigid stops against which the movable bearing house can be driven by the mill screw. Such a setting of the desired zero space, however, involves several problems which are difiicult to solve. Of course the driving motor of the mill screw can be manually stopped when it is seen that the movable bearing housing comes into contact with the said rigid stop. Because of the considerable movable masses in the movable bearing housing, the mill screw and other movable mechanical parts, however, the movement of the bearing housing and the mill screw will continue for a certain short period after the driving motor of the mill screw has been stopped. Because of this the bearing housing will be pressed by the mill screw against the rigid stop with a certain force, the magnitude of which cannot be determined. The magnitude of this force will also vary from one setting to the other because of unavoidable variations in the friction in the mechanical guiding means for the movable bearing housing and the mill screw. It is of course also possible to automatize this setting process by arranging a member which in a suitable way senses when the movable bearing housing comes into contact with the rigid stop and thus automatically breaks the voltage to the driving motor of the mill screw. It is, however, obvious that such an automation of the process would in no way solve the above mentioned problems since there is still no possibility of determining the force with which the movable bearing housing will be pressed against the rigid stop.

Because of the springing in the system, thus, the roller r position during milling will vary with the force. This uncertainty as to the position of the rolls is often greater than is permissible with respect to the requirements called for by the gauge tolerance of the rolled material. In order to determine the rolling space with suificient certainty, therefore, the force against the rigid stops must be sensed.

The object of the present invention is to elfect an arrangement for automatically and with great accuracy setting the desired rolling space between two rolls arranged in the above mentioned way. The device according to the invention is characterized substantially in that a pressure sensing measuring device is so connected with the movable bearing housing that it is resiliently influenced by a force which is dependent upon the force with which the bearing housing is pressed by the mechanical driving means against the mechanically rigid stop, and that the difference between the output magnitude of the measuring device and a stable reference magnitude is arranged to guide the speed of the driving means. According to the invention the said difference is suitably transferred to a regulator determining the speed of the driving means,

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as the desired value, which regulator is further transferred to a magnitude depending on the speed of the driving means, as the actual value. In this way an automatic adjustment of a sensed pressure and thus a sensed distance is obtained between the pair of rolls during operation.

In the following the invention will be more closely described with reference to the accompanying drawing in which FIGURE 1 shows, by way of example, one embodiment of the invention, while FIGURE 2 shows, by way of example, a suitable method of mounting the measuring body of the pressure sensing device in the movable bearing housing and FIGURE 3 is a circuit diagram.

The device shown in FIGURE 1 comprises two rolls, the lower of which, 1, is mounted in a stationary bearing housing comprising a part 2, while the upper one 3 is mounted in a movable bearing housing comprising a part 4. The movable bearing housing 4 is suspended in hydraulic cylinders 5 which influence the bearing housing 4 with an upwardly directed force. The stationary bear ing housing 2 is provided with rigid stops 6 to determine a certain desired rolling space, the so-called zero space, between the two rolls 1 and 3. The movable bearing housing 4 can, by means of a mill screw comprising a part 7 which is driven by an electric motor 8, be displaced in relation to the stationary bearing housing 2. The motor 8 is fed from a regulator 9 which is controlled depending on a control voltage supplied between the clamps 10. The device comprises further a means 11 for connecting the pressure sensitive measuring device 12 to the network and delivering a direct current output voltage on terminals 13 dependent upon the force which is acting upon the pressure measuring device 12, as will be better seen from FIGURE 3. The pressure sensitive measuring body 12 is mechanically resiliently linked between the mill screw 7 and the movable bearing housing 4 so that the mill screw 7 influences the movable bearing housing 4 via this pressure sensitive measuring body 12. Between the clamps 13 an output voltage is maintained from the pressure sensitive measuring device, which is proportional to the pressure which influences the measuring body 12. 14 designates a potentiometer connected to a constant direct voltage source, from which a constant adjustable reference voltage may be taken out. 15 is a tachometer-generator, driven from the driving motor 8 of the mill screw, which thus leaves a voltage proportional to the speed of the mill screw. The regulator 9 is influenced partly by the difference between the output voltage over the clamps 13 from the pressure sensing measuring device and the reference voltage adjusted on the potentiometer 14. This difference influences the regulator 9 as a desired voltage value. The regulator 9 is also influenced in the opposite direction by the voltage from the tachometer-generator 15 which acts as an actual voltage value. Consequently, the regulator 9 will maintain the number of revolutions of the driving motor 8, and thus the speed of the mill screw 7, at a value which is determined by the difference between the output voltage from the pressure sensing measuring device and the reference voltage from the potentiometer 14.

The setting of the desired zero space between the rolls 1 and 3 is carried out so that the movable bearing housing 4 with the roll 3 of the mill screw 7 is driven against the rigid stops 6. Before the bearing housing 4 comes into contact with the stops 6, the pressure sensing measuring body 12 is influenced by a constant force which is equal to the force from the hydraulic cylinders 5 and the friction forces in the mechanical guiding means for the bearing housing 4 and the mill screw 7. A constant output voltage is thus maintained over the clamps 13 from the pressure sensing measuring device and the mill screw 7 will be driven with a constant speed determined by the difference between this output voltage over the clamps 13 and the reference voltage from the potentiometer 14. As soon as the bearing housing 4 comes into contact with the rigid stops 6 and thus stops, however, the force which influences the measuring body 12 will increase. Because the measuring body is resiliently mounted between the mill screw and the movable bearing 4, the pressure force which influences the pressure sensing measuring body 12 will in crease in proportion to the downwards movement of the mill screw 7. In this way an increasing output voltage is obtained between the clamps 13 from the pressure sensing measuring device, which is proportional to the movement of the mill screw 7. The difference between the output voltage over the clamps 13 and the reference voltage from the potentiometer 14 thus decreases so that the number of revolutions of the driving motor 8 and thus the speed of the mill screw 7 decrease correspondingly until the mentioned difference becomes zero and the number of revolutions of the driving motor 8 also becomes zero. If, for any reason, the mill screw should be driven still further so that the output voltage over the clamps 13 becomes greater than the reference voltage from the potentiometer 14, the driving motor 8 will be driven in the opposite direction by the regulator, until an equilibrium has been again reached for which the difference between the voltage over the clamps 13 and the voltage from the potentiometer 14- is zero. Thus the movable bearing housing 4 has, by means of the arrangement shown according to the invention, been automatically driven against the rigid stops 6 to press against these with a pressure force, determined with great accuracy,

the magnitude of which can be adjusted by the potentiometer 14.

FIGURE 2, which is a section through the line AA in FIGURE 1, shows schematically a suitable method according to the invention of mounting the pressure sensing measuring body of the measuring device in the bearing housing 4. FIGURE 2 shows the mill screw 7 and the movable bearing housing 4. In a notch in the movable bearing housing 4 is placed a container 16 in which a pressure sensitive measuring body 17 is mounted. The container 16 consists of a block which is provided with a notch 18 in which the pressure sensitive measuring body 17 is mounted between two opposite sides. Further, the block is so formed that the block part 19, on which the mill screw 7 operates, just as the block part 20, which acts as underlayer for the pressure sensitive measuring body 17, is resilient in the pressure sensing direction of the measuring body. The force which influences the pressure sensitive measuring body 17 Will thus be dependent upon the movement of themill screw 7 in relation to the movable bearing housing 4. The pressure sensitive measuring body is advantageously of the type described in US. Patent No. 2,895,332 comprising a measuring body of magnetostrictive material, said measuring body being provided with four substantially parallel ducts, two coils each threaded through a pair of said ducts and linking said body so that the two coils form a cross-like pattern, means for applying said forces to said measuring body so that at least a component of force is exerted in a direction which lies in a plane at an angle of substantially 45 to the winding planes of said coils, an alternating current source G connected to one of said coils and a voltage sensing means M connected to the other coil. During normal rolling the mill screw must influence the movable bearing housing 4 with a force which is many times greater than that required for adjusting the zero space between the rolls. So that the pressure sensitive measuring device shall have as small dimensions as possible and still be sensitive it is, however, desirable that it does not need to be dimensioned for these great pressure forces. The pressure sensitive measuring body according to the invention is therefore mounted in the manner shown in FIG- URE 2 so that when the force with which the mill screw 7 influences the container 16 exceeds a certain value, the

resilience in the container 16 becomes so great that the mill screw 7 will operate directly on the movable bearing housing 4.

The connection between means 11 and the pressure sensitive device 12 is shown in more detail in FIGURE 3. A network N feeds the primary winding 31 of a transformer 32 in means 11. The secondary winding 33 is connected to an exciting coil 34 in the pressure sensitive measuring body 17. A measuring coil 35 in said body 17 is connected to primary winding 36 of another transformer 37 in means 11. The secondary windings 38 of said transformer 37 are connected to a rectifier bridge 39, the output of which is connected to terminals 13. The network also feeds the primary winding 4t? of a third transformer 4-1. A rectifier birdge 43 is connected to the secondary winding 42 of the transformer 41. The output of the bridge 43 is connected to the potentiometer 14.

Of course, it is not necessary for the pressure sensitive measuring body to be mounted precisely in the way shown in FIGURE 2, but other resilient mounting methods are naturally suitable. In the same way, pressure sensitive measuring bodies of other types than that mentioned above could of course be used.

Neither is it necessary to use a tachometer-generator connected to the driving motor of the mill screw to maintain an actual magnitude for the regulator 9 proportional to the speed of the mill screw 7. Naturally, any other magnitude which is dependent on the number of revolutions of the driving motor, for example armature voltage or armature current, may be used for this purpose. 7 It is also unnecessary to transfer to the regulator 9 a control magnitude dependent on the number of revolutions of the driving motor 8, but the regulator 9 may be directly controlled solely by thedifference between the output voltage from the pressure sensitive measuring device and the reference voltage from the potentiometer 14. With such an arrangement, however, it is more diflicult to maintain a stable and accurate setting of the zero space. In order to obtain this with such an arrangement, the maximum diiference between the output voltage from the clamps 13 and the reference voltage from the potentiometer 14 should be considerably greater than the value of the control voltage which completely controls the regulator 9, so that the control area of the regulator is first entered when the difference between the output voltage 13 andjhe reference voltage from the potentiometer 14 is very small.

I claim:

1. In a rolling mill, a plurality of parts including bearing housings mounted for movement towards and away from each other, a roll mounted in each housing, means to move at least one of the housings towards and from the other housing, the rolls being so positioned in said housings that said housings are engageable during relative movement of the housings towards each other, driving means to produce such relative movement, a pressure sensitive measuring device, said device being positioned with its sensing direction coincident with the direction of relative movement of the housings, said mill including two of said parts relatively movable with respect to each other between which the device is arranged and which are adapted to engage one another when said device is subjected to a predetermined pressure substantially lower than the rolling pressure, means to give a constant reference magnitude, and means responsive to the difference between said constant magnitude and the output of said device to control said driving means.

2. A device as claimed in claim 1 in which one of said parts has a recess therein receiving said device and forming a part of said mounting means.

3. In a device according to claim 1, a regulator, means to apply to such regulator the difference between the first mentioned difference and a magnitude dependent upon the speed of the driving means, said regulator determining the speed of the driving means.

4. Device according to claim 1, in which the pressure sensing measuring device is positioned between the driving means and the bearing housing so that the driving means acts on the bearing housing through the measuring device.

5. In a rolling mill, bearing housings mounted for movement towards and away from each other, a roll mounted in each housing, means to move at least one of the housings towards and from the other housing, the rolls being so positioned in said housings that said housings are engageable during relative movement of the housings towards each other, driving means to produce such relative movement, said moving means including a part mounted for relative movement with respect to one of said housings in a direction coinciding with the direction of relative movement of said housings, such housing and said part having facing surfaces transverse to such direction, one of such surfaces having a recess therein, and a pressure sensitive measuring device mounted in said recess in a position in which its sensing direction coincides with such direction, said device having a normal thickness slightly greater than the depth of the recess but being compressible by a pressure substantially less than the rolling pressure to a thickness equal to such depth, means to produce a constant reference magnitude, and means responsive to the difference between said constant magnitude and the output of said measuring device to control said driving means.

References Cited by the Examiner UNITED STATES PATENTS 2,575,590 11/51 Goulding 80-563 2,659,154 11/53 Rendel 80-561 2,909,717 10/59 Hulls et al. 80-56.1 3,049,036 8/62 Wallace et a1 80-562 WILLIAM J. STEPHENSON, Primary Examiner.

LEON PEAR, Examiner. 

1. IN A ROLLING MILL, A PLURALITY OF PARTS INCLUDING BEARING HOUSINGS MOUNTED FOR MOVEMENT TOWARDS AND AWAY FROM EACH OTHER, A ROLL MOUNTED IN EACH HOUSING, MEANS TO MOVE AT LEAST ONE OF THE HOUSINGS TOWARDS AND FROM THE OTHER HOUSING, THE ROLLS BEING SO POSITIONED IN SAID HOUSINGS THAT SAID HOUSINGS ARE ENGAGEABLE DURING RELATIVE MOVEMENT OF THE HOUSINGS TOWARDS EACH OTHER, DRIVING MEANS TO PRODUCE SUCH RELATIVE MOVEMENT, A PRESSURE SENSITIVE MEASURING DEVICE, SAID DEVICE BEING POSITIONED WITH ITS SENSING DIRECTION COINCIDENT WITH THE DIRECTION OF RELATIVE MOVEMENT OF THE HOUSINGS, SAID MILL INCLUDING TWO OF SAID PARTS RELATIVELY MOVABLE WITH RESPECT TO EACH OTHER BETWEEN WHICH THE DEVICE IS ARRANGED AND WHICH ARE ADAPTED TO ENGAGE ONE ANOTHER WHEN SAID DEVICE IS SUBJECTED TO A PREDETERMINED PRESSURE SUBSTANTIALLY LOWER THAN THE ROLLING PRESSURE, MEANS TO GIVE A CONSTANT REFERENCE MAGNITUDE, AND MEANS RESPONSIVE TO THE DIFFERENCE BETWEEN SAID CONSTANT MAGNITUDE AND THE OUTPUT OF SAID DEVICE TO CONTROL SAID DRIVING MEANS. 